Controlled atmosphere apparatus or equipment is useful where a prescribed atmosphere must be maintained. Such apparatus is useful in a number of different industries and applications. For example, a controlled atmosphere apparatus having an anaerobic atmosphere may be useful in microbiological laboratories in the process of aiding the identification of certain types of bacteria. A controlled atmosphere apparatus having an atmosphere that resembles the conditions inside the body may be useful in incubating zygotes as part of the In Vitro Fertilisation (IVF) procedure.
A controlled atmosphere apparatus typically comprises at least one chamber with a prescribed atmosphere. The prescribed atmosphere within the chamber is commonly created and maintained by regulating the temperature, humidity and gas concentrations.
It will be appreciated that a controlled atmosphere apparatus must be designed to allow for the manual manipulation of specimens (for example, the loading, unloading and inspection of specimens) without any deleterious effects to the atmosphere within the chamber. Previously, this has been achieved by providing one or more user access ports comprising a long glove or gauntlet sealed to a porthole. The glove is extendable into the chamber from the porthole of the user access port so as to allow an operator to manipulate a specimen within the chamber. Although the glove prevents both the ingress of air into the chamber and outflow of gas from the cabinet, this solution is not ideal because air becomes trapped within the glove as the operator extends his arm and hand into the glove and so his movement is restricted. Also, due to the nature of the glove, the operator's sensitivity of touch is somewhat limited. Moreover, operators complain that their hand becomes clammy when wearing the gloves for a given period of time.
Some of the problems associated with using gloves may be overcome by alternatively providing one or more user access ports with an arm tube comprising an open cuff (bare-hand type tubes). The arm tube is extendable into the chamber from the porthole of the user access port and the open cuff is configured to allow the operator's hand to extend through the arm tube and provide a seal around an operator's arm or wrist such that he can use his bare hand to manipulate a specimen within the chamber. Although the arm tube provides improvements over the gloves, air still becomes trapped within the arm tube as the operator extends his hands and arms through the arm tubes. Hence, an operator's movement is restricted. Critically, there is also a risk that air may ingress into the chamber and gas may leak from the chamber as the operator extends his hand through the open cuff and/or if the seal between the open cuff and the operator's arm or wrist is not maintained.
Accordingly, no matter which type of user access port system is used, it is necessary to evacuate the glove/arm tube prior to use. Air is conventionally evacuated from the glove/arm tube using a vacuum pump. A pressured inert gas may additionally or alternatively be pumped into the glove/arm tube. Typically, operators are advised to repeat the evacuation process at least twice so as to ensure the air within the glove/arm tube is sufficiently removed.
However, despite the risks associated with spoiling the prescribed atmosphere within a cabinet and the problems associated with restricted movement and touch, it has been found that the evacuation process is sometimes ignored by an operator because it is time consuming and complex.
It has also become apparent that certain operators find the use of the long gloves or arm tubes unnerving and disconcerting because they feel uncontrollably attached to the apparatus. Indeed, the level of agitation may become so significant that an operator may even avoid using a controlled atmosphere apparatus with gloves/arm tubes.